4 files changed, 29 insertions, 0 deletions
diff --git a/clang/docs/LibASTMatchersReference.html b/clang/docs/LibASTMatchersReference.html
index bf186145d6d..8be0aa9eb82 100644
--- a/clang/docs/LibASTMatchersReference.html
+++ b/clang/docs/LibASTMatchersReference.html
@@ -285,6 +285,17 @@ Example matches X, S, the anonymous union type, i, and U;
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('namespaceAliasDecl0')"><a name="namespaceAliasDecl0Anchor">namespaceAliasDecl</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1NamespaceAliasDecl.html">NamespaceAliasDecl</a>&gt;...</td></tr>
+<tr><td colspan="4" class="doc" id="namespaceAliasDecl0"><pre>Matches a declaration of a namespace alias.
+
+Given
+  namespace test {}
+  namespace alias = ::test;
+namespaceAliasDecl()
+  matches "namespace alias" but not "namespace test"
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('namespaceDecl0')"><a name="namespaceDecl0Anchor">namespaceDecl</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1NamespaceDecl.html">NamespaceDecl</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="namespaceDecl0"><pre>Matches a declaration of a namespace.
 
diff --git a/clang/include/clang/ASTMatchers/ASTMatchers.h b/clang/include/clang/ASTMatchers/ASTMatchers.h
index 46f30f06d5a..cb10daf89e3 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchers.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchers.h
@@ -292,6 +292,18 @@ const internal::VariadicDynCastAllOfMatcher<Decl, NamedDecl> namedDecl;
 ///   matches "namespace {}" and "namespace test {}"
 const internal::VariadicDynCastAllOfMatcher<Decl, NamespaceDecl> namespaceDecl;
 
+/// \brief Matches a declaration of a namespace alias.
+///
+/// Given
+/// \code
+///   namespace test {}
+///   namespace alias = ::test;
+/// \endcode
+/// namespaceAliasDecl()
+///   matches "namespace alias" but not "namespace test"
+const internal::VariadicDynCastAllOfMatcher<Decl, NamespaceAliasDecl>
+    namespaceAliasDecl;
+
 /// \brief Matches C++ class declarations.
 ///
 /// Example matches \c X, \c Z
diff --git a/clang/lib/ASTMatchers/Dynamic/Registry.cpp b/clang/lib/ASTMatchers/Dynamic/Registry.cpp
index 1544b084344..8601a3804d1 100644
--- a/clang/lib/ASTMatchers/Dynamic/Registry.cpp
+++ b/clang/lib/ASTMatchers/Dynamic/Registry.cpp
@@ -288,6 +288,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(memberPointerType);
   REGISTER_MATCHER(methodDecl);
   REGISTER_MATCHER(namedDecl);
+  REGISTER_MATCHER(namespaceAliasDecl);
   REGISTER_MATCHER(namespaceDecl);
   REGISTER_MATCHER(namesType);
   REGISTER_MATCHER(nestedNameSpecifier);
diff --git a/clang/unittests/ASTMatchers/ASTMatchersTest.cpp b/clang/unittests/ASTMatchers/ASTMatchersTest.cpp
index 5bc66f6c030..b4fc09084b8 100644
--- a/clang/unittests/ASTMatchers/ASTMatchersTest.cpp
+++ b/clang/unittests/ASTMatchers/ASTMatchersTest.cpp
@@ -4369,6 +4369,11 @@ TEST(NS, Anonymous) {
   EXPECT_TRUE(matches("namespace {}", namespaceDecl(isAnonymous())));
 }
 
+TEST(NS, Alias) {
+  EXPECT_TRUE(matches("namespace test {} namespace alias = ::test;",
+                      namespaceAliasDecl(hasName("alias"))));
+}
+
 TEST(NNS, MatchesTypes) {
   NestedNameSpecifierMatcher Matcher = nestedNameSpecifier(
     specifiesType(hasDeclaration(recordDecl(hasName("A")))));